This invention relates to an overheat and overload sensing device, and particularly to a sensing device that combines a thermal breaker sensor to a circuit breaker for integral design. In the case of overheat the present device can respond automatically to cut off a local circuit that makes the breaker become overloaded to break off the power supply.
A fuse or no fuse breaker is usually applied in a power supply circuit for protection of electrical appliances against damage when overloading. However, the usual breaker seems useless in the case of overheat. For instance, U.S. Pat. No. 5,539,371, U.S. Pat. No. 5,453,725 and U.S. Pat. No. 5,694,106 are concerned with the abovesaid automatic breaker that can shut down power supply if, and only if, a circuit is overloaded electrically. An ordinary fuse or automatic breaker cannot respond to overheat of household electrothermal appliances, such as a drinking water supplier, juice maker, or coffee pot, etc. as long as electric current is kept under rated value. A coffee pot, for example, usually contains at least a water tank and a heating device for heating water in the tank. When power is supplied, the heating device will consecutively heat the water tank. When water in the tank is used up or evaporated and the tank becomes empty, if the heating device is not stopped in time under this circumstance, internal parts off the drinking water supplier will probably be destroyed, or the supplier itself may be burnt, becoming thoroughly damaged, and incurring unexpected danger.